OBJECTIVES: 1. To determine the effect of varying concentrations of strontium with and without fluoride, on tooth morphology and dental caries in the rat. Strontium concentrations in drinking water fed to the rats will be based upon known values existing in naturally occurring waters shown to be associated with low caries in human studies. 2. To assess the pre- and post-eruptive effects of strontium by feeding the element at different stages of tooth development. 3. To study influence of Sr and F uptake in rat enamel and the relation to caries. METHODS: Sprague-Dawley rats will be fed a cariogenic diet (MIT 200) supplemented with varying concentrations of strontium and fluoride in the water supplies. Experiments will consider strontium administration during pregnancy, lactation and post-weaning. Caries will be assessed by method of Keyes. Variations in molar morphology will be assessed by standardized tooth measurements, using an optical comparator coupled with a projected image. Chemical analysis of teeth will be completed for strontium and fluoride of surface enamel to determine uptakes. Effects of strontium upon growth of the rat liver incisor and structure of enamel and dentine will be assessed.